Lawesson's reagent (LR) is a chemical compound used in organic synthesis as a thiation agent. Lawesson's reagent was first made popular by Sven-Olov Lawesson, who did not, however, invent it. Lawesson's reagent was first made in 1956 during a systematic study of the reactions of arenes with P4S10.[1]
Samples give a strong odor of hydrogen sulfide owing to partial hydrolysis. One common and effective method of destroying the foul smelling residues is to use an excess of sodium hypochlorite (chlorine bleach).
Mechanism of actionEdit
Lawesson's reagent has a four membered ring of alternating sulfur and phosphorus atoms. The central phosphorus/sulfur four-membered ring dissociates to form two reactive dithiophosphine ylides (R-PS2). Much of the chemistry of Lawessons's reagent is in fact the chemistry of this reactive intermediate.
In general, the more electron rich a carbonyl is, the faster the carbonyl group will be converted into the corresponding thiocarbonyl by Lawesson's reagent.
ApplicationsEdit
The chemistry of Lawesson's reagent and related substances has been reviewed by several times.[3][4][5][6] The main use of Lawesson's reagent is the thionation of carbonyl compounds. For instance, Lawesson's reagent will convert a carbonyl into a thiocarbonyl.[7] Additionally, Lawesson's reagent has been used to thionate enones, esters,[8]lactones,[9]amides, lactams,[10] and quinones.
In one study, reaction of maltol with LR results in a selective oxygen replacement in two positions.[11]
^Lecher, H. Z.; Greenwood, R. A.; Whitehouse, K. C.; Chao, T. H. (1956). "The Phosphonation of Aromatic Compounds with Phosphorus Pentasulfide". J. Am. Chem. Soc.78 (19): 5018. doi:10.1021/ja01600a058.
^Cherkasov, R. A.; Kutyrev, G. A.; Pudovik, A. N. (1985). "Tetrahedron report number 186 Organothiophosphorus reagents in organic synthesis". Tetrahedron (Review). 41 (13): 2567. doi:10.1016/S0040-4020(01)96363-X.
^Foreman, M.S.; Woollins, J.D. (2000). "Organo-P–S and P–Se heterocycles". J. Chem. Soc., Dalton Trans. (10): 1533–1543. doi:10.1039/b000620n.
^ abMartin Jesberger; Thomas P. Davis; Leonie Barner (2003). "Applications of Lawesson's Reagent in Organic and Organometallic Syntheses". Synthesis (Review). 2003 (13): 1929–1958. doi:10.1055/s-2003-41447.
^Cava, M. P.; Levinson, M. I. (1985). "Thionation reactions of Lawesson's reagents". Tetrahedron. 41 (22): 5061–5087. doi:10.1016/S0040-4020(01)96753-5.
^Pedersen, B. S.; Scheibye, S.; Nilsson, N. H.; Lawesson, S.-O. (1978). "Studies on organophosphorus compounds XX. syntheses of thioketones". Bull. Soc. Chim. Belg.87 (3): 223–228. doi:10.1002/bscb.19780870310.
^Jones, B. A.; Bradshaw, J. S. (1984). "Synthesis and reduction of thiocarboxylic O-esters". Chem. Rev. (Review). 84 (84): 17. doi:10.1021/cr00059a002.
^Scheibye, S.; Kristensen, J.; Lawesson, S.-O. (1979). "Studies on organophosphorus compounds XXVII. Synthesis of thiono-, thiolo- and dithiolactones". Tetrahedron. 35 (11): 1339–1343. doi:10.1016/0040-4020(79)85027-9.
^Shabana, R.; Scheibye, S.; Clausen, K.; Olesen, S. O.; Lawesson, S.-O. (1980). "Studies on organophosphorus compounds XXXI. Synthesis of thiolactams and thioimides". Nouveau Journal de Chimie. 1980 (4): 47.
^Brayton, D.; Jacobsen, F. E.; Cohen, S. M.; Farmer, P. J. (2006). "A novel heterocyclic atom exchange reaction with Lawesson's reagent: a one-pot synthesis of dithiomaltol". Chemical Communications. 2006 (2): 206–208. doi:10.1039/b511966a. PMID 16372107.
lawesson, reagent, chemical, compound, used, organic, synthesis, thiation, agent, first, made, popular, sven, olov, lawesson, however, invent, first, made, 1956, during, systematic, study, reactions, arenes, with, p4s10, namesiupac, name, methoxyphenyl, dithia. Lawesson s reagent LR is a chemical compound used in organic synthesis as a thiation agent Lawesson s reagent was first made popular by Sven Olov Lawesson who did not however invent it Lawesson s reagent was first made in 1956 during a systematic study of the reactions of arenes with P4S10 1 Lawesson s reagent NamesIUPAC name 2 4 Bis 4 methoxyphenyl 1 3 2 4 dithiadiphosphetane 2 4 disulfidePreferred IUPAC name 2 4 Bis 4 methoxyphenyl 1 3 2 4 dithiadiphosphetane 2 4 dithioneOther names Lawesson reagent LRIdentifiersCAS Number 19172 47 5 Y3D model JSmol Interactive imageChemSpider 79346 YECHA InfoCard 100 038 944EC Number 242 855 4PubChem CID 87949UNII A4125MQ8RX YCompTox Dashboard EPA DTXSID4066460InChI InChI 1S C14H14O2P2S4 c1 15 11 3 7 13 8 4 11 17 19 21 18 20 22 17 14 9 5 12 16 2 6 10 14 h3 10H 1 2H3 YKey CFHGBZLNZZVTAY UHFFFAOYSA N YInChI 1 C14H14O2P2S4 c1 15 11 3 7 13 8 4 11 17 19 21 18 20 22 17 14 9 5 12 16 2 6 10 14 h3 10H 1 2H3Key CFHGBZLNZZVTAY UHFFFAOYABSMILES S P1 SP S S1 c2ccc OC cc2 c3ccc OC cc3PropertiesChemical formula C 14H 14O 2P 2S 4Molar mass 404 45 g mol 1Appearance Slightly yellow powderMelting point 228 231 C 442 448 F 501 504 K Solubility in water InsolubleHazardsGHS labelling PictogramsSignal word WarningHazard statements H261 H302 H312 H332Precautionary statements P231 P232 P261 P264 P270 P271 P280 P301 P312 P302 P352 P304 P312 P304 P340 P312 P322 P330 P363 P370 P378 P402 P404 P501Related compoundsRelated thiation agents Hydrogen sulfide Phosphorus pentasulfideExcept where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa Y verify what is Y N Infobox references Contents 1 Preparation 2 Mechanism of action 3 Applications 4 See also 5 References 6 External linksPreparation EditLawesson s reagent is commercially available It can also be conveniently prepared in the laboratory by heating a mixture of anisole with phosphorus pentasulfide until the mixture is clear and no more hydrogen sulfide is formed 2 then recrystallized from toluene or xylene Samples give a strong odor of hydrogen sulfide owing to partial hydrolysis One common and effective method of destroying the foul smelling residues is to use an excess of sodium hypochlorite chlorine bleach Mechanism of action EditLawesson s reagent has a four membered ring of alternating sulfur and phosphorus atoms The central phosphorus sulfur four membered ring dissociates to form two reactive dithiophosphine ylides R PS2 Much of the chemistry of Lawessons s reagent is in fact the chemistry of this reactive intermediate nbsp In general the more electron rich a carbonyl is the faster the carbonyl group will be converted into the corresponding thiocarbonyl by Lawesson s reagent Applications EditThe chemistry of Lawesson s reagent and related substances has been reviewed by several times 3 4 5 6 The main use of Lawesson s reagent is the thionation of carbonyl compounds For instance Lawesson s reagent will convert a carbonyl into a thiocarbonyl 7 Additionally Lawesson s reagent has been used to thionate enones esters 8 lactones 9 amides lactams 10 and quinones nbsp In one study reaction of maltol with LR results in a selective oxygen replacement in two positions 11 nbsp A combination of silver perchlorate and Lawesson s reagent is able to act as an oxophilic Lewis acid with the ability to catalyze the Diels Alder reaction of dienes with a b unsaturated aldehydes in some cases alcohols may be converted to thiols by treatment with Lawesson s reagent 12 Lawesson s reagent reacts with sulfoxides to form thioethers 5 See also EditWoollins reagentReferences Edit Lecher H Z Greenwood R A Whitehouse K C Chao T H 1956 The Phosphonation of Aromatic Compounds with Phosphorus Pentasulfide J Am Chem Soc 78 19 5018 doi 10 1021 ja01600a058 Thomsen I Clausen K Scheibye S Lawesson S O 1984 Thiation with 2 4 Bis 4 methoxyphenyl 1 3 2 4 Dithiadiphosphetane 2 4 disulfide N Methylthiopyrrolidone Organic Syntheses 62 158 doi 10 15227 orgsyn 062 0158 Cherkasov R A Kutyrev G A Pudovik A N 1985 Tetrahedron report number 186 Organothiophosphorus reagents in organic synthesis Tetrahedron Review 41 13 2567 doi 10 1016 S0040 4020 01 96363 X Foreman M S Woollins J D 2000 Organo P S and P Se heterocycles J Chem Soc Dalton Trans 10 1533 1543 doi 10 1039 b000620n a b Martin Jesberger Thomas P Davis Leonie Barner 2003 Applications of Lawesson s Reagent in Organic and Organometallic Syntheses Synthesis Review 2003 13 1929 1958 doi 10 1055 s 2003 41447 Cava M P Levinson M I 1985 Thionation reactions of Lawesson s reagents Tetrahedron 41 22 5061 5087 doi 10 1016 S0040 4020 01 96753 5 Pedersen B S Scheibye S Nilsson N H Lawesson S O 1978 Studies on organophosphorus compounds XX syntheses of thioketones Bull Soc Chim Belg 87 3 223 228 doi 10 1002 bscb 19780870310 Jones B A Bradshaw J S 1984 Synthesis and reduction of thiocarboxylic O esters Chem Rev Review 84 84 17 doi 10 1021 cr00059a002 Scheibye S Kristensen J Lawesson S O 1979 Studies on organophosphorus compounds XXVII Synthesis of thiono thiolo and dithiolactones Tetrahedron 35 11 1339 1343 doi 10 1016 0040 4020 79 85027 9 Shabana R Scheibye S Clausen K Olesen S O Lawesson S O 1980 Studies on organophosphorus compounds XXXI Synthesis of thiolactams and thioimides Nouveau Journal de Chimie 1980 4 47 Brayton D Jacobsen F E Cohen S M Farmer P J 2006 A novel heterocyclic atom exchange reaction with Lawesson s reagent a one pot synthesis of dithiomaltol Chemical Communications 2006 2 206 208 doi 10 1039 b511966a PMID 16372107 Nishio Takehiko 1989 A novel transformation of alcohols to thiols Journal of the Chemical Society Chemical Communications 1989 4 205 206 doi 10 1039 C39890000205 External links Edit Lawesson s Reagent Organic Chemistry Portal Retrieved 2007 10 16 Retrieved from https en wikipedia org w index php title Lawesson 27s reagent amp oldid 1107892784, wikipedia, wiki, book, books, library,
